Chemorheology of allophanate‐cured polyurethane rubber

Tsuyoshi Nagai, Hidetoshi Oikawa, Kenkichi Murakami

Research output: Contribution to journalArticlepeer-review

Abstract

Chemical stress relaxation (CSR) of allophanate‐cured polyurethane (PU) was measured under two kinds of degradation conditions: (1) degradation in butylamine (BuNH2)/dimethyl sulfoxide solution; (2) degradation at high temperature in nitrogen. The allophanate groups of the crosslink sites in PU networks are selectively cleaved by BuNH2, and CSR is not influenced by the crosslink density within experimental error. This suggests the validity of Tobolosky's method for distinguishing between random scission along network chains and the cleavage of crosslinks from the dependence of CSR on crosslink densities. In addition, CSR of PU samples degraded at high temperature in nitrogen was also found to be independent of the crosslink density. It follows that thermal degradation of PU networks occurs by the cleavage of crosslink sites in the same manner. CSR is compared with the relative degree of thermal degradation of PU sample, determined by‐the amine‐decomposition method and the swelling method. Consequently, the total (or residual) crosslink density of degraded PU networks corresponds essentially to the intermittent CSR.

Original languageEnglish
Pages (from-to)809-817
Number of pages9
JournalJournal of Polymer Science Part B: Polymer Physics
Volume27
Issue number4
DOIs
Publication statusPublished - 1989 Mar

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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